1. Field of the Invention
The present invention relates to multifunction frequency counters which may be manufactured on a single semiconductor chip and more particularly to multifunction frequency counters which function as frequency counters, period measuring devices and counters.
2. Description of the Prior Art
Presently the circuitry for most multifunction frequency counters is implemented by the use of a collection of conventional logic elements. These logic elements include a BCD ripple up counter, which is described in the National Semiconductor CMOS Databook, an A/C coupled amplifier, which is also described in the National Semiconductor CMOS Databook, "D" flip-flops, which are described in the RCA COS/MOS Integrated Circuits Databook, a Crystal Oscillator, which is described in the RCA COS/MOS Integrated Circuits Databook, a Johnson Counter, which is described in the RCA COS/MOS Integrated Circuits Databook, and a Binary ripple counter, which is also described in the RCA COS/MOS Integrated Circuits Databook. These logic elements are electrically coupled to form a multifunction frequency counter.
Another multifunction frequency counter is formed when an Intersil Complementary MOS Oscillator Controller, ICM7207A, is electrically coupled to an Intersil Frequency Counter, IMC7208. This combination of logic element enables the multifunction frequency counter to obtain seven significant digits when measuring frequencies over one megaHertz.
U.S. Pat. No. 4,047,114, entitled Digital Detector, issued to Richard A. Lane and Donald K. Fronek on Sept. 6, 1977, teaches a digital detector for detecting the presence of selected frequencies in an input signal. The digital detector includes a counting device having an input and an output, a NAND gate having a first input and a second input and an output, with the output of the NAND gate being electrically coupled to the input of the counting device, and a shaping device having an input for receiving the input frequency signals and an output for providing a shaped gating pulse. The output of the shaping device is electrically coupled to the first input of the NAND gate. The digital detector also includes a pulse generator having an output electrically coupled to the second input of the NAND gate and a gating input electrically coupled to the output of the shaping device and a decoder circuit electrically coupled to the output of the counting device for responding to the output of the counting device to provide output pulses which are a function of the detector input frequency signals.
U.S. Pat. No. 3,854,277, entitled Electronic Stop-Watch and Timepiece, issued to Toshihide Samejima and Yasuhiro Ooi on Dec. 17, 1974, teaches an electronic timekeeping device capable of functioning both as a stop-watch and as a timepiece. A signal generator includes a crystal oscillator and provides a base frequency which is divided in a plurality of stages of frequency dividers and is then counted on counters that effect a time count displayed visually on a time display. The time count is applied from the counters to display elements through latch circuits which constitute storage circuits under the control of latch controlling device when the device function as a stop-watch and through these latch or storage circuits.
A Mostek MOS Counter Time-Base Circuit, MK 5009p, is a highly versatile MOS oscillator which is manufactured by a depletion-load, ion-implantation process and P-channel technology. With an input frequency on one Megahertz, the MOS Counter Time-Base Circuit provides the basic time periods necessary for most frequency measuring instruments.
None of the above-described circuits integrates all of the functions of a multifunction frequency counter onto one complementary metal oxide silicon/large scale integration, CMOS/LSI, chip. Furthermore there is no single multifunction frequency counter chip presently available that requires no external active components.